1. Field of the Invention
The present invention relates to motor-driven compressors formed integrally with a compressor device for compressing refrigerant and a motor for driving the compressor device, and more particularly, to motor-driven compressors that are suitable for use in air conditioning systems for vehicles.
2. Description of Related Art
Motor-driven compressors are driven by power supply, for example, an external power source, such as a battery. Motor-driven compressors formed integrally with a compression portion and a motor for compressing refrigerant are known in the art. In such known compressors, a drive circuit for controlling the driving of the motor is separated from the compression portion and the motor, and an inverter is supplied to the motor for converting power supplied from a power source into a suitable current for the motor. Such an inverter generally comprises a plurality of switching elements. The switching elements may generate a significant amount of heat caused by, for example, electrical loss in the switching elements. Therefore, an air-cooled or a water-cooled type inverter has been used in such known motor driven compressors. In the air-cooled type inverter, a radiator or a fan is employed. In the water-cooled type inverter, a water cooling radiator and water circulating pipes are employed. Such additional equipment increases cost of manufacturing the automotive air-conditioning system.
A need has arisen to provide motor-driven compressors with drive circuits that do not require additional cooling equipment, such as radiators and fans.
In an embodiment of this invention, a motor-driven compressor is formed integrally with a compressor device for compressing refrigerant and a motor for driving the compressor device. The motor-driven compressor comprises a drive circuit. The drive circuit controls the driving of the motor. The drive circuit is provided on an exterior surface wall of a refrigerant suction passage, and the drive circuit is coated by or buried within an insulating resin material.
Objects, features, and advantages of embodiments of this invention will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings.